The most plausible reason for the association of the Watson and Buchanan names is outlined in The History of the Ancient Surname of Buchanan and of Ancient Scottish Surnames; More Particularly the Clans [Ref. 2],which was written by William Buchanan of Auchmar and published in 1793. In it, he describes how the Buchanan family of Lenny is the oldest cadet branch of the Buchanan family. The first mention of a Buchanan laird of Lenny is in a charter dated 1247, which refers to an Allan Buchanan de Lenny. One of his descendants, John Buchanan, the second laird of Lenny called John, is stated as being laird during the reign of King Robert III, who reigned between 1390 and 1406. One of John’s sons was called Walter, although he was referred to as “Wattie in Calintuy, being the name of the place of his residence”. Wattie’s son John lived in the parish of Luss and “according to the ordinary custom of those, and even of the present times among highlanders, had his surname changed into a patronimical one, derived from his father’s proper name, being thence termed John MacWattie”. John had nine sons and the MacWatties became “in a small process of time pretty numerous”. Many of these MacWatties and their descendants retained the name, although some branches did later reassume the Buchanan name. As discussed on Page 4, the name “Watson” is the anglicised version of “MacWattie”; although we have not yet followed these MacWatties forward to see if they anglicised their names in any significant numbers, it is likely that at some point the Clan Buchanan Society included all variants of "MacWattie" in their sept list.